Old Jan 23, 20, 3:50 pm
Join Date: Jan 2015
Location: Bregenz, Austria
Programs: AA, BAEC, Alaska, Flying Blue, United, IHG, Hilton
Posts: 2,950
3-bedded rooms are just generally not a thing in the UK.

​​​In the rest of the English speaking world, USA, Canada, Australia, NZ, etc. you can usually find a "family" room with, for example, a double and two singles, but in the UK (and really the rest of Europe), it's not really an option outside of cheap B&Bs or hostels.
In chain hotels, the best you can hope for is a twin with a sofa bed or a rollaway.

Try a quick search of the relevant property's TripAdvisor reviews and enter a search term like "rollaway" or "extra bed".
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